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Abstract We study the propagation and impacts of a strong density pulse through the magnetosphere during 11:40–12:00 UT near the peak of a geomagnetic storm on 3 February 2022. Using the Space Weather Modeling Framework Geospace global simulation, we show how the energy transport in the magnetosphere is enhanced promptly after the pulse arrival at the dayside magnetosphere, causing enhanced flows in the magnetotail prior to the compression reaching the tail region. The flows are shown to transport energy into the inner magnetosphere and couple to the dawn sector ionosphere, where the magnetic field variations caused large geomagnetically induced currents. We discuss the characteristics of pulse‐driven disturbances in the magnetosphere—ionosphere system, and argue that despite some similarities, the activity is distinct from substorms. 

Abstract Solar wind conditions in the heliosphere are altered by solar wind transients such as shocks and interplanetary coronal mass ejections (ICMEs). The interactions of coherent solar wind structures such as the heliospheric current sheet (HCS) with the transients remain incompletely understood, however. Here, we report the first in situ spacecraft observations showing two magnetic reconnection exhausts in the HCS embedded in the sheath region of an ICME. The dropout (presence) of strahl electrons indicates the disconnection (connection) of an exhaust region from (to) Sun. We perform a multispacecraft analysis, which shows that reconnection in the HCS embedded in an ICME sheath can operate in a quasi-steady manner at 1 au, with the observations across the outflow regions showing a good correlation with the Walén relation. The two reconnecting HCS crossings in the ICME sheath are compared to two other HCS crossings, one in the sheath and one in the solar wind upstream of the ICME shock, which show no magnetic reconnection signatures. These results highlight interplanetary transients as space plasma environments that can host dynamics infrequently observed in the solar wind at Earth’s orbit. 

Abstract Solar wind drives magnetospheric dynamics through coupling with the geospace system at the magnetopause. While upstream fluctuations correlate with geomagnetic activity, their impact on the magnetopause energy transfer is an open question. In this study, we examine three‐dimensional global magnetospheric simulations using the Geospace configuration of the Space Weather Modeling Framework. We examine the effects of solar wind fluctuations during a substorm event by running the model with four different driving conditions that vary in fluctuation frequency spectrum. We demonstrate that upstream fluctuations intensify the energy exchange at the magnetopause increasing both energy flux into and out of the system. The increased energy input is reflected in ground magnetic indices. Moreover, the fluctuations impact the magnetopause dynamics by regulating the energy exchange between the polar caps and lobes and energy transport within the magnetotail neutral sheet.